This is for people new to Blackrock these are commands to change race, faction and to customize a players character.
.u changefaction - allows you to between factions
.u changereace - allows you to change race with the same the faction
.u customize - allows to you to customize the appearance of your character e.g. change facials features, skin tone, sex etc.
You could just use the shorthand .u change for race and customisation (customisation is a subset of the race change), and .u changef for the faction one